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Department of Quantitative Biomedicine

The Kümmerli group shows coordination of siderophore gene expression in clonal P. aeruginosa cells

Coordination of siderophore gene expression among clonal cells of the bacterium Pseudomonas aeruginosa

See Mridha & Kümmerli, Commun. Biol.

An open question in microbiology is whether seemingly coordinated group-level responses, such as biofilm formation, actually mirror what individual cells do. To tackle this question, the Kümmerli group used single-cell microscopy to simultaneously quantify the investment of individual P. aeruginosa cells into two public goods. Using gene expression as a proxy for investment, these bacterial cells initially show no coordination in siderophore investment, but rather high heterogeneity and bi-modality. However, with increasing cell density, gene expression becomes more homogenised across cells, with positive associations in siderophore gene expression across cells and with cell-to-cell variation correlating with cellular metabolic states. This suggests that siderophore-mediated signalling aligns behavior of individual bacteria over time and spurs a coordinated three-phase siderophore investment cycle, covering the time spans from low to high population density, steered by the various interconnected regulatory mechanisms governing siderophore synthesis.

Fig. 4: Heterogeneity in siderophore gene expression declines over time